Boot failure

Today I attemped to install windows xp on and external hard disc. I currently have Windows 7 installed but I wanted to have an OS I could take with me. I wasn't sure on how to do it, but I attemped it anyway (bad idea...). What I did was to shrink the current partition on the external drive and create a 20GB chunk of unpartitioned space. I then proceeded to insert my Windows XP disc and install on the unpartitioned space. After the install Windows XP would not boot, so I tried to boot without the external hard drive attached and I got this error message.

"Windows could not start because of a computer disk hardware configuration problem. Could not read from the selected boot disk. Check boot path and disk hardware. Please check the Windows documentation about hardware disk configuration and your hardware reference manuals for additional information."

After getting this message i attempted to abandon the project and on a different machine deleted the recent Windows XP partition. Up until this point I have had no luck getting my Windows 7 OS to boot. I have tried resetting the BIOS, performing a system recovery, and I have even called HP (the manufacturer) whose only answer was to send me a set restore discs. I know all the data is still there because i used my Linux live cd and checked. If there is anyone out there who can help I would greatly appreciate it! Thanks for all your help in advance.

An earlier Windows operating system has been installed after Windows Vista or Windows 7 was installed. In this scenario, the computer starts by using Windows NT Loader (NTLDR) instead of Windows Boot Manager (Bootmgr.exe).

To make sure you should run it two times, once like this:

bootrec /Fixboot

which should already be enough to make you boot 7 and - if not enough - also as:

It seems I've run into a problem. The CD's that HP sent me aren't the discs I was hoping for. They sent me Discs that were designed specifically to format my hard drive and reinstall 7 the way it came from the factory. There is no option for command prompt or system recovery.

Is there any way to run Bootrec.exe without buying a whole new installation of Windows 7?